sandbox/win/src/interception.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 // For information about interceptions as a whole see
   6 // http://dev.chromium.org/developers/design-documents/sandbox .
   7
   8 #include <set>
   9
  10 #include "sandbox/win/src/interception.h"
  11
  12 #include "base/logging.h"
  13 #include "base/memory/scoped_ptr.h"
  14 #include "base/strings/string16.h"
  15 #include "base/win/pe_image.h"
  16 #include "base/win/windows_version.h"
  17 #include "sandbox/win/src/interception_internal.h"
  18 #include "sandbox/win/src/interceptors.h"
  19 #include "sandbox/win/src/sandbox.h"
  20 #include "sandbox/win/src/service_resolver.h"
  21 #include "sandbox/win/src/target_interceptions.h"
  22 #include "sandbox/win/src/target_process.h"
  23 #include "sandbox/win/src/wow64.h"
  24
  25 namespace {
  26
  27 // Standard allocation granularity and page size for Windows.
  28 const size_t kAllocGranularity = 65536;
  29 const size_t kPageSize = 4096;
  30
  31 // Find a random offset within 64k and aligned to ceil(log2(size)).
  32 size_t GetGranularAlignedRandomOffset(size_t size) {
  33   CHECK_LE(size, kAllocGranularity);
  34   unsigned int offset;
  35
  36   do {
  37     rand_s(&offset);
  38     offset &= (kAllocGranularity - 1);
  39   } while (offset > (kAllocGranularity - size));
  40
  41   // Find an alignment between 64 and the page size (4096).
  42   size_t align_size = kPageSize;
  43   for (size_t new_size = align_size / 2;  new_size >= size; new_size /= 2) {
  44     align_size = new_size;
  45   }
  46   return offset & ~(align_size - 1);
  47 }
  48
  49 }  // namespace
  50
  51 namespace sandbox {
  52
  53 SANDBOX_INTERCEPT SharedMemory* g_interceptions;
  54
  55 // Table of the unpatched functions that we intercept. Mapped from the parent.
  56 SANDBOX_INTERCEPT OriginalFunctions g_originals = { NULL };
  57
  58 // Magic constant that identifies that this function is not to be patched.
  59 const char kUnloadDLLDummyFunction[] = "@";
  60
  61 InterceptionManager::InterceptionData::InterceptionData() {
  62 }
  63
  64 InterceptionManager::InterceptionData::~InterceptionData() {
  65 }
  66
  67 InterceptionManager::InterceptionManager(TargetProcess* child_process,
  68                                          bool relaxed)
  69     : child_(child_process), names_used_(false), relaxed_(relaxed) {
  70   child_->AddRef();
  71 }
  72 InterceptionManager::~InterceptionManager() {
  73   child_->Release();
  74 }
  75
  76 bool InterceptionManager::AddToPatchedFunctions(
  77     const wchar_t* dll_name, const char* function_name,
  78     InterceptionType interception_type, const void* replacement_code_address,
  79     InterceptorId id) {
  80   InterceptionData function;
  81   function.type = interception_type;
  82   function.id = id;
  83   function.dll = dll_name;
  84   function.function = function_name;
  85   function.interceptor_address = replacement_code_address;
  86
  87   interceptions_.push_back(function);
  88   return true;
  89 }
  90
  91 bool InterceptionManager::AddToPatchedFunctions(
  92     const wchar_t* dll_name, const char* function_name,
  93     InterceptionType interception_type, const char* replacement_function_name,
  94     InterceptorId id) {
  95   InterceptionData function;
  96   function.type = interception_type;
  97   function.id = id;
  98   function.dll = dll_name;
  99   function.function = function_name;
 100   function.interceptor = replacement_function_name;
 101   function.interceptor_address = NULL;
 102
 103   interceptions_.push_back(function);
 104   names_used_ = true;
 105   return true;
 106 }
 107
 108 bool InterceptionManager::AddToUnloadModules(const wchar_t* dll_name) {
 109   InterceptionData module_to_unload;
 110   module_to_unload.type = INTERCEPTION_UNLOAD_MODULE;
 111   module_to_unload.dll = dll_name;
 112   // The next two are dummy values that make the structures regular, instead
 113   // of having special cases. They should not be used.
 114   module_to_unload.function = kUnloadDLLDummyFunction;
 115   module_to_unload.interceptor_address = reinterpret_cast<void*>(1);
 116
 117   interceptions_.push_back(module_to_unload);
 118   return true;
 119 }
 120
 121 bool InterceptionManager::InitializeInterceptions() {
 122   if (interceptions_.empty())
 123     return true;  // Nothing to do here
 124
 125   size_t buffer_bytes = GetBufferSize();
 126   scoped_ptr<char[]> local_buffer(new char[buffer_bytes]);
 127
 128   if (!SetupConfigBuffer(local_buffer.get(), buffer_bytes))
 129     return false;
 130
 131   void* remote_buffer;
 132   if (!CopyDataToChild(local_buffer.get(), buffer_bytes, &remote_buffer))
 133     return false;
 134
 135   bool hot_patch_needed = (0 != buffer_bytes);
 136   if (!PatchNtdll(hot_patch_needed))
 137     return false;
 138
 139   g_interceptions = reinterpret_cast<SharedMemory*>(remote_buffer);
 140   ResultCode rc = child_->TransferVariable("g_interceptions",
 141                                            &g_interceptions,
 142                                            sizeof(g_interceptions));
 143   return (SBOX_ALL_OK == rc);
 144 }
 145
 146 size_t InterceptionManager::GetBufferSize() const {
 147   std::set<base::string16> dlls;
 148   size_t buffer_bytes = 0;
 149
 150   std::list<InterceptionData>::const_iterator it = interceptions_.begin();
 151   for (; it != interceptions_.end(); ++it) {
 152     // skip interceptions that are performed from the parent
 153     if (!IsInterceptionPerformedByChild(*it))
 154       continue;
 155
 156     if (!dlls.count(it->dll)) {
 157       // NULL terminate the dll name on the structure
 158       size_t dll_name_bytes = (it->dll.size() + 1) * sizeof(wchar_t);
 159
 160       // include the dll related size
 161       buffer_bytes += RoundUpToMultiple(offsetof(DllPatchInfo, dll_name) +
 162                                             dll_name_bytes, sizeof(size_t));
 163       dlls.insert(it->dll);
 164     }
 165
 166     // we have to NULL terminate the strings on the structure
 167     size_t strings_chars = it->function.size() + it->interceptor.size() + 2;
 168
 169     // a new FunctionInfo is required per function
 170     size_t record_bytes = offsetof(FunctionInfo, function) + strings_chars;
 171     record_bytes = RoundUpToMultiple(record_bytes, sizeof(size_t));
 172     buffer_bytes += record_bytes;
 173   }
 174
 175   if (0 != buffer_bytes)
 176     // add the part of SharedMemory that we have not counted yet
 177     buffer_bytes += offsetof(SharedMemory, dll_list);
 178
 179   return buffer_bytes;
 180 }
 181
 182 // Basically, walk the list of interceptions moving them to the config buffer,
 183 // but keeping together all interceptions that belong to the same dll.
 184 // The config buffer is a local buffer, not the one allocated on the child.
 185 bool InterceptionManager::SetupConfigBuffer(void* buffer, size_t buffer_bytes) {
 186   if (0 == buffer_bytes)
 187     return true;
 188
 189   DCHECK(buffer_bytes > sizeof(SharedMemory));
 190
 191   SharedMemory* shared_memory = reinterpret_cast<SharedMemory*>(buffer);
 192   DllPatchInfo* dll_info = shared_memory->dll_list;
 193   int num_dlls = 0;
 194
 195   shared_memory->interceptor_base = names_used_ ? child_->MainModule() : NULL;
 196
 197   buffer_bytes -= offsetof(SharedMemory, dll_list);
 198   buffer = dll_info;
 199
 200   std::list<InterceptionData>::iterator it = interceptions_.begin();
 201   for (; it != interceptions_.end();) {
 202     // skip interceptions that are performed from the parent
 203     if (!IsInterceptionPerformedByChild(*it)) {
 204       ++it;
 205       continue;
 206     }
 207
 208     const base::string16 dll = it->dll;
 209     if (!SetupDllInfo(*it, &buffer, &buffer_bytes))
 210       return false;
 211
 212     // walk the interceptions from this point, saving the ones that are
 213     // performed on this dll, and removing the entry from the list.
 214     // advance the iterator before removing the element from the list
 215     std::list<InterceptionData>::iterator rest = it;
 216     for (; rest != interceptions_.end();) {
 217       if (rest->dll == dll) {
 218         if (!SetupInterceptionInfo(*rest, &buffer, &buffer_bytes, dll_info))
 219           return false;
 220         if (it == rest)
 221           ++it;
 222         rest = interceptions_.erase(rest);
 223       } else {
 224         ++rest;
 225       }
 226     }
 227     dll_info = reinterpret_cast<DllPatchInfo*>(buffer);
 228     ++num_dlls;
 229   }
 230
 231   shared_memory->num_intercepted_dlls = num_dlls;
 232   return true;
 233 }
 234
 235 // Fills up just the part that depends on the dll, not the info that depends on
 236 // the actual interception.
 237 bool InterceptionManager::SetupDllInfo(const InterceptionData& data,
 238                                        void** buffer,
 239                                        size_t* buffer_bytes) const {
 240   DCHECK(buffer_bytes);
 241   DCHECK(buffer);
 242   DCHECK(*buffer);
 243
 244   DllPatchInfo* dll_info = reinterpret_cast<DllPatchInfo*>(*buffer);
 245
 246   // the strings have to be zero terminated
 247   size_t required = offsetof(DllPatchInfo, dll_name) +
 248                     (data.dll.size() + 1) * sizeof(wchar_t);
 249   required = RoundUpToMultiple(required, sizeof(size_t));
 250   if (*buffer_bytes < required)
 251     return false;
 252
 253   *buffer_bytes -= required;
 254   *buffer = reinterpret_cast<char*>(*buffer) + required;
 255
 256   // set up the dll info to be what we know about it at this time
 257   dll_info->unload_module = (data.type == INTERCEPTION_UNLOAD_MODULE);
 258   dll_info->record_bytes = required;
 259   dll_info->offset_to_functions = required;
 260   dll_info->num_functions = 0;
 261   data.dll._Copy_s(dll_info->dll_name, data.dll.size(), data.dll.size());
 262   dll_info->dll_name[data.dll.size()] = L'\0';
 263
 264   return true;
 265 }
 266
 267 bool InterceptionManager::SetupInterceptionInfo(const InterceptionData& data,
 268                                                 void** buffer,
 269                                                 size_t* buffer_bytes,
 270                                                 DllPatchInfo* dll_info) const {
 271   DCHECK(buffer_bytes);
 272   DCHECK(buffer);
 273   DCHECK(*buffer);
 274
 275   if ((dll_info->unload_module) &&
 276       (data.function != kUnloadDLLDummyFunction)) {
 277     // Can't specify a dll for both patch and unload.
 278     NOTREACHED();
 279   }
 280
 281   FunctionInfo* function = reinterpret_cast<FunctionInfo*>(*buffer);
 282
 283   size_t name_bytes = data.function.size();
 284   size_t interceptor_bytes = data.interceptor.size();
 285
 286   // the strings at the end of the structure are zero terminated
 287   size_t required = offsetof(FunctionInfo, function) +
 288                     name_bytes + interceptor_bytes + 2;
 289   required = RoundUpToMultiple(required, sizeof(size_t));
 290   if (*buffer_bytes < required)
 291     return false;
 292
 293   // update the caller's values
 294   *buffer_bytes -= required;
 295   *buffer = reinterpret_cast<char*>(*buffer) + required;
 296
 297   function->record_bytes = required;
 298   function->type = data.type;
 299   function->id = data.id;
 300   function->interceptor_address = data.interceptor_address;
 301   char* names = function->function;
 302
 303   data.function._Copy_s(names, name_bytes, name_bytes);
 304   names += name_bytes;
 305   *names++ = '\0';
 306
 307   // interceptor follows the function_name
 308   data.interceptor._Copy_s(names, interceptor_bytes, interceptor_bytes);
 309   names += interceptor_bytes;
 310   *names++ = '\0';
 311
 312   // update the dll table
 313   dll_info->num_functions++;
 314   dll_info->record_bytes += required;
 315
 316   return true;
 317 }
 318
 319 bool InterceptionManager::CopyDataToChild(const void* local_buffer,
 320                                           size_t buffer_bytes,
 321                                           void** remote_buffer) const {
 322   DCHECK(NULL != remote_buffer);
 323   if (0 == buffer_bytes) {
 324     *remote_buffer = NULL;
 325     return true;
 326   }
 327
 328   HANDLE child = child_->Process();
 329
 330   // Allocate memory on the target process without specifying the address
 331   void* remote_data = ::VirtualAllocEx(child, NULL, buffer_bytes,
 332                                        MEM_COMMIT, PAGE_READWRITE);
 333   if (NULL == remote_data)
 334     return false;
 335
 336   SIZE_T bytes_written;
 337   BOOL success = ::WriteProcessMemory(child, remote_data, local_buffer,
 338                                       buffer_bytes, &bytes_written);
 339   if (FALSE == success || bytes_written != buffer_bytes) {
 340     ::VirtualFreeEx(child, remote_data, 0, MEM_RELEASE);
 341     return false;
 342   }
 343
 344   *remote_buffer = remote_data;
 345
 346   return true;
 347 }
 348
 349 // Only return true if the child should be able to perform this interception.
 350 bool InterceptionManager::IsInterceptionPerformedByChild(
 351     const InterceptionData& data) const {
 352   if (INTERCEPTION_INVALID == data.type)
 353     return false;
 354
 355   if (INTERCEPTION_SERVICE_CALL == data.type)
 356     return false;
 357
 358   if (data.type >= INTERCEPTION_LAST)
 359     return false;
 360
 361   base::string16 ntdll(kNtdllName);
 362   if (ntdll == data.dll)
 363     return false;  // ntdll has to be intercepted from the parent
 364
 365   return true;
 366 }
 367
 368 bool InterceptionManager::PatchNtdll(bool hot_patch_needed) {
 369   // Maybe there is nothing to do
 370   if (!hot_patch_needed && interceptions_.empty())
 371     return true;
 372
 373   if (hot_patch_needed) {
 374 #if SANDBOX_EXPORTS
 375     // Make sure the functions are not excluded by the linker.
 376 #if defined(_WIN64)
 377     #pragma comment(linker, "/include:TargetNtMapViewOfSection64")
 378     #pragma comment(linker, "/include:TargetNtUnmapViewOfSection64")
 379 #else
 380     #pragma comment(linker, "/include:_TargetNtMapViewOfSection@44")
 381     #pragma comment(linker, "/include:_TargetNtUnmapViewOfSection@12")
 382 #endif
 383 #endif
 384     ADD_NT_INTERCEPTION(NtMapViewOfSection, MAP_VIEW_OF_SECTION_ID, 44);
 385     ADD_NT_INTERCEPTION(NtUnmapViewOfSection, UNMAP_VIEW_OF_SECTION_ID, 12);
 386   }
 387
 388   // Reserve a full 64k memory range in the child process.
 389   HANDLE child = child_->Process();
 390   BYTE* thunk_base = reinterpret_cast<BYTE*>(
 391                          ::VirtualAllocEx(child, NULL, kAllocGranularity,
 392                                           MEM_RESERVE, PAGE_NOACCESS));
 393
 394   // Find an aligned, random location within the reserved range.
 395   size_t thunk_bytes = interceptions_.size() * sizeof(ThunkData) +
 396                        sizeof(DllInterceptionData);
 397   size_t thunk_offset = GetGranularAlignedRandomOffset(thunk_bytes);
 398
 399   // Split the base and offset along page boundaries.
 400   thunk_base += thunk_offset & ~(kPageSize - 1);
 401   thunk_offset &= kPageSize - 1;
 402
 403   // Make an aligned, padded allocation, and move the pointer to our chunk.
 404   size_t thunk_bytes_padded = (thunk_bytes + kPageSize - 1) & ~(kPageSize - 1);
 405   thunk_base = reinterpret_cast<BYTE*>(
 406                    ::VirtualAllocEx(child, thunk_base, thunk_bytes_padded,
 407                                     MEM_COMMIT, PAGE_EXECUTE_READWRITE));
 408   CHECK(thunk_base);  // If this fails we'd crash anyway on an invalid access.
 409   DllInterceptionData* thunks = reinterpret_cast<DllInterceptionData*>(
 410                                     thunk_base + thunk_offset);
 411
 412   DllInterceptionData dll_data;
 413   dll_data.data_bytes = thunk_bytes;
 414   dll_data.num_thunks = 0;
 415   dll_data.used_bytes = offsetof(DllInterceptionData, thunks);
 416
 417   // Reset all helpers for a new child.
 418   memset(g_originals, 0, sizeof(g_originals));
 419
 420   // this should write all the individual thunks to the child's memory
 421   if (!PatchClientFunctions(thunks, thunk_bytes, &dll_data))
 422     return false;
 423
 424   // and now write the first part of the table to the child's memory
 425   SIZE_T written;
 426   bool ok = FALSE != ::WriteProcessMemory(child, thunks, &dll_data,
 427                                           offsetof(DllInterceptionData, thunks),
 428                                           &written);
 429
 430   if (!ok || (offsetof(DllInterceptionData, thunks) != written))
 431     return false;
 432
 433   // Attempt to protect all the thunks, but ignore failure
 434   DWORD old_protection;
 435   ::VirtualProtectEx(child, thunks, thunk_bytes,
 436                      PAGE_EXECUTE_READ, &old_protection);
 437
 438   ResultCode ret = child_->TransferVariable("g_originals", g_originals,
 439                                             sizeof(g_originals));
 440   return (SBOX_ALL_OK == ret);
 441 }
 442
 443 bool InterceptionManager::PatchClientFunctions(DllInterceptionData* thunks,
 444                                                size_t thunk_bytes,
 445                                                DllInterceptionData* dll_data) {
 446   DCHECK(NULL != thunks);
 447   DCHECK(NULL != dll_data);
 448
 449   HMODULE ntdll_base = ::GetModuleHandle(kNtdllName);
 450   if (!ntdll_base)
 451     return false;
 452
 453   base::win::PEImage ntdll_image(ntdll_base);
 454
 455   // Bypass purify's interception.
 456   wchar_t* loader_get = reinterpret_cast<wchar_t*>(
 457                             ntdll_image.GetProcAddress("LdrGetDllHandle"));
 458   if (loader_get) {
 459     if (!GetModuleHandleEx(GET_MODULE_HANDLE_EX_FLAG_FROM_ADDRESS |
 460                                GET_MODULE_HANDLE_EX_FLAG_UNCHANGED_REFCOUNT,
 461                            loader_get, &ntdll_base))
 462       return false;
 463   }
 464
 465   if (base::win::GetVersion() <= base::win::VERSION_VISTA) {
 466     Wow64 WowHelper(child_, ntdll_base);
 467     if (!WowHelper.WaitForNtdll())
 468       return false;
 469   }
 470
 471   char* interceptor_base = NULL;
 472
 473 #if SANDBOX_EXPORTS
 474   interceptor_base = reinterpret_cast<char*>(child_->MainModule());
 475   HMODULE local_interceptor = ::LoadLibrary(child_->Name());
 476 #endif
 477
 478   ServiceResolverThunk* thunk;
 479 #if defined(_WIN64)
 480   thunk = new ServiceResolverThunk(child_->Process(), relaxed_);
 481 #else
 482   base::win::OSInfo* os_info = base::win::OSInfo::GetInstance();
 483   if (os_info->wow64_status() == base::win::OSInfo::WOW64_ENABLED) {
 484     if (os_info->version() >= base::win::VERSION_WIN8)
 485       thunk = new Wow64W8ResolverThunk(child_->Process(), relaxed_);
 486     else
 487       thunk = new Wow64ResolverThunk(child_->Process(), relaxed_);
 488   } else if (os_info->version() >= base::win::VERSION_WIN8) {
 489     thunk = new Win8ResolverThunk(child_->Process(), relaxed_);
 490   } else {
 491     thunk = new ServiceResolverThunk(child_->Process(), relaxed_);
 492   }
 493 #endif
 494
 495   std::list<InterceptionData>::iterator it = interceptions_.begin();
 496   for (; it != interceptions_.end(); ++it) {
 497     const base::string16 ntdll(kNtdllName);
 498     if (it->dll != ntdll)
 499       break;
 500
 501     if (INTERCEPTION_SERVICE_CALL != it->type)
 502       break;
 503
 504 #if SANDBOX_EXPORTS
 505     // We may be trying to patch by function name.
 506     if (NULL == it->interceptor_address) {
 507       const char* address;
 508       NTSTATUS ret = thunk->ResolveInterceptor(local_interceptor,
 509                                                it->interceptor.c_str(),
 510                                                reinterpret_cast<const void**>(
 511                                                &address));
 512       if (!NT_SUCCESS(ret))
 513         break;
 514
 515       // Translate the local address to an address on the child.
 516       it->interceptor_address = interceptor_base + (address -
 517                                     reinterpret_cast<char*>(local_interceptor));
 518     }
 519 #endif
 520     NTSTATUS ret = thunk->Setup(ntdll_base,
 521                                 interceptor_base,
 522                                 it->function.c_str(),
 523                                 it->interceptor.c_str(),
 524                                 it->interceptor_address,
 525                                 &thunks->thunks[dll_data->num_thunks],
 526                                 thunk_bytes - dll_data->used_bytes,
 527                                 NULL);
 528     if (!NT_SUCCESS(ret))
 529       break;
 530
 531     DCHECK(!g_originals[it->id]);
 532     g_originals[it->id] = &thunks->thunks[dll_data->num_thunks];
 533
 534     dll_data->num_thunks++;
 535     dll_data->used_bytes += sizeof(ThunkData);
 536   }
 537
 538   delete(thunk);
 539
 540 #if SANDBOX_EXPORTS
 541   if (NULL != local_interceptor)
 542     ::FreeLibrary(local_interceptor);
 543 #endif
 544
 545   if (it != interceptions_.end())
 546     return false;
 547
 548   return true;
 549 }
 550
 551 }  // namespace sandbox